The Universal Mobile Telecommunications System (UMTS) specifies Q.2630 as the control protocol used for establishing and releasing circuit switched Application Adaptation Layer type 2 (AAL-2) bearer channels. UMTS voice and circuit switched data are carried in a compressed discontinuous manner. These streams are ideal candidates for AAL-2 Virtual Channel Connections (VCCs).
ITU-T Q.2630 is a transport control protocol designed to control ATM (Asynchronous Transfer Mode) AAL-2 connections. AAL-2 provides for multiplexing multiple low bit rate and low latency data streams onto a single ATM virtual circuit. Q.2630 defines an AAL-2 VCC as a path. A path is identified by a Path Identity (PID). A single path carries multiple AAL-2 channels, each channel referenced by a Channel Identifier (CID).
ATM AAL-2 connections may be controlled by the Q.2630 bearer control protocol. Transmission savings may be realized by carrying voice traffic generated in a Time Division Multiplexed (TDM) network over a more efficient AAL-2 ATM network. At the transition from the TDM network to the AAL-2 network, a media gateway acts as an interface between the AAL-2 channel and the TDM channel.
When a voice path is to be established between a calling party and a called party, the call originating and call terminating nodes may select different communication paths. For example, the originating node may select a TDM circuit associated with a particular media gateway while the terminating node may select an ATM VCC associated with a different media gateway. This causes a problem in establishing the voice path which may require the use of switching equipment between the media gateways.